Assembly line control system

ABSTRACT

An assembly line control system, and more particularly, an automotive assembly line storage and lot controlled system is disclosed. A communications network is overlaid onto a manufacturing assembly line. The assembly line includes a number of readers and processing stations to determine and confirm the identity of vehicles passing proximate to the readers and processing stations, and the vehicles&#39; build instructions, status, position, condition, defect and repair history, etc. This information is stored in a computer database. Based on the information stored about the vehicles, the status of inventories, production schedules and the like, a routing of the vehicles through the manufacturing process is determined and implemented. The assembly line incorporates various storage loop and shunting lanes so that members of a lot of vehicles, having similar build instructions, are more likely to be placed into contact with each other, reducing possible parts changeovers, meeting production schedules, accommodating a shortfall in parts availability, etc.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of application Ser. No.09/368,254, filed Aug. 3, 1999, by inventors Rick Madden et al. Thisapplication is related to a United States patent application for aninvention entitled Zone Inspection Manufacturing Line, filed Aug. 3,1999, Ser. No. 09/368,256, the inventor is Marc Aston; and the contentsof which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention relates to an assembly line control system and,more particularly, to an automotive assembly line storage and lotcontrol system.

BACKGROUND OF THE INVENTION

[0003] In conventional assembly lines, and automotive assembly lines inparticular, a continuous feed of partially completed assemblies, such asan automobile, is passed through, typically, a large number of assemblystations. Each assembly, or vehicle as the case may be, typically has aninstruction or build sheet associated with the particular assembly. Thebuild sheet includes instructions as to the processes that need to beperformed, and the locations to which the assembly should betransported. The build sheet is typically a print out of a computerrecord for a particular vehicle that is attached, directly orindirectly, to the vehicle. A vehicle also has associated with it anassembly sheet. The assembly sheet identifies the various parts orcomponents that must be installed for the particular vehicle to whichthe assembly sheet is associated. Consequently, the assembly sheetidentifies the parts that are to be installed and the build sheetcontains the instructions as to where and what processes are to be usedin putting the parts identified on the assembly sheet together.

[0004] Recently the automotive industry has embraced two disparatemanufacturing technologies: just-in-time (JIT) production and masscustomization.

[0005] JIT production involves the co-ordination of parts supplies tothe manufacturing plant and to “line side” (that is, locationsphysically proximate to the manufacturing assembly line making partsavailable for installation on/in the assembly) in an effort to reduceinventories and, consequently, costs. As is known in the art, JITproduction may require several shipments of the same part, component orassembly, from the supplier (which may, for example, be another plant ofthe assembly manufacturer, another assembly line in the samemanufacturing plant, or a separate or outside parts supplier, such asthe Tier I suppliers to the large automobile manufacturers like Honda™).These parts shipments may and often are, due to manufacturing ordelivery difficulties, delayed in their arrival at the manufacturingplant. As a result of these delays, and the associated low inventoryproblems, it is not uncommon for the delay in a single day's shipmentsor even a single shipment of parts to severely impact plantmanufacturing and production schedules.

[0006] Mass customization is one of many terms to describe the processof building many variations of the same vehicle brand, such as a Honda™Civic™, on the same assembly line, having the same platform or basicvehicle chassis. Moreover, other separate vehicle brands, such as theAcura™ 1.6EL™, which may share the same platform as another vehicle butrequire significantly different build sheets and instructions, may alsobe manufactured on the same assembly as the Honda™ Civic™ in order toreduce manufacturing costs. As a result of mass customization, it is notuncommon for a single platform to spawn thousands of variations amongsta number of different vehicle brands. These variations require acorresponding number of different parts to be made available to theassembly line in order to fulfil the build sheet instructions. It shouldbe noted that the term “parts” is used very generically to include anytype of component that may be affixed, applied or otherwise impact theparticular vehicle manufactured. A “part” may include, for example, thefluids, the paint type, the paint colour, the wheel size, the exhaustsystem, the engine size and configuration, the transmission, the numberof doors, the seat selection(s), etc.

[0007] To accommodate JIT and mass customization simultaneouslytypically requires a large number parts to made available at a singleworkstation, such as for example, the sound system (radio) installationstation. However, due to physical limitations in line side space, manymethods of manufacturing have been attempted to limit the number ofparts changeovers. That is, a parts changeover is the removal from lineside of one set of parts, such as economy sound system, with areplacement, at line side, of another set of parts, such as an upgradedor luxury sound system. To limit the number of changeovers, similarvehicle brands with similar configurations are, conventionally scheduledto be manufactured in lots or groups. That is, a production schedule isdeveloped and implemented to group together those vehicles that have asimilar vehicle brand and are configured or “optioned” by the customersin a similar fashion. In this manner, the number of different parts atline side required to manufacture the vehicles of a particular lot aresignificantly reduced. Nevertheless, the parts at line side, wheneverthere is a changeover from one lot to another, must be changed toaccommodate the build instructions for the next lot of vehicles. Forexample, when a particular station completes its operations on the lastvehicle of a first lot and is about to commence performing operations onthe first vehicle of second lot, the line side parts located proximateto this station typically must be changed to accommodate the vehicle lotchangeover.

[0008] Difficulties with the above described assembly line and methodand often are encountered when a vehicle fails an inspection test andmust be repaired or whenever part shortages or build changes must beimplemented. As is well known in the art, partially completed vehicles,or vehicle assemblies, typically are inspected at one or more pointsduring manufacture to identify defects. As a result of theseinspections, a vehicle assembly failing inspection will, typically, beremoved from the assembly line and the defect repaired. The repairedvehicle will then be re-inserted into the vehicle assembly line. As aresult of the various inspections, removals from the assembly line,repairs and re-insertions, members of the lots of vehicles typically get“jumbled”. That is, a repaired vehicle may be inserted into an availableposition on an assembly line in the middle of a different lot ofvehicles with vastly different build instructions from that of therepaired vehicle. Consequently, parts must be made available line sideat the remaining workstations (that is, those workstations downstream ofthe insertion point) in order for the assembly of the repaired vehicleto be completed in accordance with the repaired vehicle's buildinstructions. This often results in the assembly line slowing down orstopping so that the parts control systems may provide the proper partsand components to the various workstations encountering this repairedvehicle. Moreover, some parts, such as paint colors and types, mayrequire a significant delay due to any required flushing and cleaning ofthe paint system from the previous paint colour and type. For instance,if a repaired vehicle, which is to be painted white, is inserted into alot of vehicles to be painted red, the paint system (paint lines,booths, nozzles, etc.) must be purged, flushed and cleaned of anyresidual red paint prior to the painting of the repaired, and to bewhite, vehicle. This cleansing process may be quite time consuming

[0009] Another difficulty encountered in the conventional assembly linesresults from parts shortages. Should there be any difficulties in theJIT delivery system (which may, as aforementioned, result from the delayof as little as a single shipment of parts), the ability to perform aparticular build instruction may be severely impacted. This may resultin line stoppages or the removal of vehicles from the assembly lineuntil parts are conveyed to the plant and, ultimately, line side.

[0010] Another further difficulty encountered in the conventionalassembly line results from a required build instruction change. Forinstance, if production targets for a particular type of vehicle are notbeing satisfied it may be desirable to alter the order of the lots ofvehicles on the production line. If the production targets are not beingsatisfied, an alternative action would be alter the build instructionsof particular vehicles where possible.

[0011] A still further difficulty encountered with conventional assemblylines occurs when a particular part or component has been replaced (dueto shortages, supplier replacement, change in vehicle or partspecifications, etc.). In this instance, the build instructions ofvehicles on the assembly may have to be altered. However, withconventional assembly lines and the paper based build instructions, thisprocess is timely and prone to errors.

[0012] Accordingly, an assembly system which addresses theseshortcomings is desirable.

SUMMARY OF THE INVENTION

[0013] According to one aspect of the invention, there is provided Amethod of manufacturing a plurality of assemblies, said methodcomprising: forming lots of assemblies from said plurality ofassemblies; moving said lots of assemblies from a first location to asecond location; tracking the position of each assembly of a first lotof said lots as each assembly moves between said first and secondlocations; determining that an assembly of said first lot is separatedassembly of said first lot, which is an assembly separated from anotherassembly from said first lot; routing at least one of said plurality ofassemblies along an alternate path so that said separated assemblyre-unites with another assembly of said first lot.

[0014] According to another aspect of the invention, there is provided amethod of routing an assembly through a manufacturing process between afirst location and a second location, said method comprising: (a)determining a manufacturing priority of said assembly; (b) determining arouting path based on said determination of said manufacturing priority;and (c) routing said assembly according to said routing path.

[0015] According to another aspect of the invention, there is providedan assembly line comprising: a plurality of conveyors to move assembliesfrom a first point to a second point; a plurality of switching pointsinterconnecting said plurality conveyors to form a plurality of pathsfrom said first point to said second point; a controller for controllingsaid plurality of switching points and said plurality of conveyors totransfer a first assembly from said first point to said second pointalong a path which bypasses a second assembly positioned between saidfirst and second points.

[0016] According to another aspect of the invention, there is providedan assembly line comprising: a first station, having a first assemblythat is a member of a first group of assemblies positioned proximate tosaid first station; a second station, downstream of said first station,having a second assembly that is a member of a second group ofassemblies positioned proximate to said second station; a third station,downstream of said first and second stations, having a third assemblythat is a member of said first group of assemblies positioned proximateto said third station; and a router adapted to transfer said firstassembly from said first station to said third station bypassing saidsecond assembly and said second station.

[0017] According to another aspect of the invention, there is provided amethod of manufacturing an assembly on a manufacturing line, said methodcomprising: determining a level of manufacturing priority of a firstassembly, which precedes a second assembly on said manufacturing line;determining a level of manufacturing priority of said second assembly;if said manufacturing priority of said second assembly is higher thansaid manufacturing priority of said first assembly, re-ordering saidfirst and second assemblies so that said second assembly precedes saidfirst assembly on said manufacturing line.

[0018] According to another aspect of the invention, there is provided asystem for routing an assembly through an assembly process comprising aplurality of assembly lanes, said system comprising: a receiver forreceiving signals from an assembly identifier, said signals comprisingan assembly identifier unique to said assembly; said receiver forreceiving signals indicating current position of said assembly in saidassembly process; said receiver for receiving signals relating to saidassembly's current manufacturing priority; a processor, responsive to anoutput of said receiver, for determining a current route for saidassembly; and a transmitter, responsive to an output of said processor,for transmitting signals indicating said route to said plurality ofassembly lanes.

[0019] According to another aspect of the invention, there is providedcomputer software media, which, when loaded into a processor, adaptssaid processor to: receive signals from an assembly identifier, saidsignals comprising an assembly identifier unique to said assembly;receive signals relating the current position of said assembly in saidassembly process; receive signals relating to said assembly's currentmanufacturing priority; responsive to said received signals, determine acurrent route for said assembly; and transmit signals indicative of saidcurrent route to a plurality of assembly lanes.

[0020] According to another aspect of the invention, there is provided amethod of manufacturing a first and a second assembly in an assemblyprocess, said method comprising: tracking said first and secondassemblies through said assembly process; determining said firstassembly's manufacturing priority; determining said second assembly'smanufacturing priority; and if said second assembly's priority isgreater than said first assembly, positioning said second assemblydownstream of said first assembly in said assembly process.

[0021] According to another aspect of the invention, there is provided asystem for the manufacturing of a plurality of assemblies, said systemcomprising: a conveyor system for moving said assemblies from a firstposition to a second position, said conveyor system having a pluralityof paths interposed between said first and second positions; a computeradapted to assign said plurality of assemblies to lots and adapted totrack the position of each member of a first lot of said lots as eachmember moves between said first and second locations, said computer alsoadapted to determine when an assembly of said first lot is separatedfrom said first lot; and said computer adapted to route at least one ofsaid plurality of assemblies along an alternate path of said conveyorsystem so that an assembly that is separated from its lot can rejoin itslot to form a contiguous group with said other assemblies of said firstlot.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be more clearly understood afterreference to the following detailed specification read in conjunctionwith the drawings wherein:

[0023]FIG. 1A is a plan view of a first level of an automobile assemblyline constructed in accordance with one embodiment of the invention.

[0024]FIG. 1B is a plan view of a second level of an automobile assemblyline constructed in accordance with one embodiment of the invention.

[0025]FIG. 1C is a schematic of an assembly constructed in accordancewith one embodiment of the invention, incorporating the assembly linesof FIGS. 1A and 1B.

[0026]FIG. 2 is a schematic of a computer network used in conjunctionwith assembly line of FIGS. 1A and 1B.

[0027] FIGS. 3-15 are flow charts illustrating operations performed onthe assembly line of FIGS. 1A and 1B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0028] While the preferred embodiment of the invention has beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

[0029] Throughout the remainder of the specification the following termswill be used. The meanings of these terms are defined below.

[0030] PBS Painted Body Storage—illustrated in FIG. 1A as element 100A.This term refers to an area for painted and partially completedvehicles. In the embodiment described herein, the PBS area is located ona lower level below the ABS area.

[0031] ABS Assembly Body Storage—illustrated in FIG. 1B as element 100B.This ABS area, located in the herein described embodiment above the PBSarea, receives partially completed vehicles from the PBS area and FinalAssembly (AF) area and transfers these vehicles to the Final Assemblyarea and the PBS area, depending on the vehicle's status and condition

[0032] PBS STATUS A vehicle has an associated PBS status indicator thatis set to either PASS or FAIL. A passed PBS status indicates that aparticular vehicle has satisfied various quality criteria and can thenbe transferred to final assembly. A failed PBS status indicates that thevehicle has a defect that must be repaired prior to Final Assembly. ThePBS status indicator for a particular vehicle may be changed at any ofthe inspection and/or repair areas (areas 148, 150 and 154—FIG. 2). Theinspection areas perform a variety of inspection tests. The failure ofany one of these tests may result in a vehicle's PBS status beingchanged to FAIL. A vehicle that has not failed any quality inspections,or that has had all identified defects repaired, will have a PBS statusset to PASS. The PBS status indicator is stored in database 208 ofmanufacturing network 200 (FIG. 2).

[0033] PRODUCTION STATUS Each vehicle has an associated ProductionStatus indicator. The Production Status indicator can be set to one ofSCRAP, HOLD or RELEASED. A vehicle with a Production Status of SCRAPindicates that a major defect has been identified and that the vehicleshould be scrapped. A HOLD Production Status indicator represents thatthe vehicle should not, at least temporarily, continue through themanufacturing process. The vehicle may be stored off-line or on-line intemporary storage lanes (such as lanes 110—FIG. 1). A RELEASEDProduction Status indicates that the vehicle can proceed to the nextstage of the manufacturing process. This productions status may beupdated throughout the assembly process. The Production Status indicatoris stored in database 208 of manufacturing network 200 (FIG. 2). Theproduction status may be set, in the case of SCRAP, at any of thevehicle inspection areas. The production status of HOLD or RELEASED isdetermined by the manufacturing network 200 (FIG. 2), depending on thevehicle production targets, actual vehicle production statistics, thelocation of other vehicle's in a vehicle's lot (or group). TheProduction Status indicator is also stored in database 208 ofmanufacturing network 200 (FIG. 2).

[0034] AF Final Assembly. The AF area installs the various componentsonto or into the painted body such as, for example, the instrumentpanel, the suspension sub-assemblies, the glass, doors,engine/transmission assembly, etc.

[0035] LOT CONDITION Each vehicle is associated with, and is a memberof, a lot (or group). Each vehicle has an associated Lot Conditionindicator (hereinafter used interchangeably with lot condition) that canbe set to DELAYED, CURRENT or FUTURE. The Lot Condition for a particularvehicle is set with respect to the position of other members of its lotand the position that the vehicle should be in if no manufacturingdifficulties had been encountered. For example, a vehicle that isremoved from contact with other members of its lot, due to, for example,defects being identified, will lag behind its lot. That is the vehiclewill be have been DELAYED, and the vehicle's lot condition will be setaccordingly. If the vehicle is positioned in the manufacturing processwith other members of its lot that are undergoing the manufacturingprocess, the lot condition will be set to CURRENT. If a vehicle is amember of a lot that is scheduled to be processed at a later time, thevehicle's lot condition will be set to FUTURE. The Lot Conditionindicator is also stored in database 208 of manufacturing network 200(FIG. 2).

[0036] Based on a number of factors, including, for example, a vehicle'sPBS status, lot condition indicator, lot number, production status, thevehicle's manufacturing priority (that is, priority of a particularvehicle, as compared to other vehicles in assembly line 10 (FIG. 1C) canbe determined. Based on a vehicle's manufacturing priority a vehiclewill be routed through assembly line 10.

[0037] Referencing FIG. 1C, an automobile assembly line 10, embodyingone aspect of the invention, is illustrated. Generally, automobileassembly line 10 comprises: body-in-white area 12, paint area 14,storage assembly line 100 and final assembly area 16. A body-in-white,that is an unpainted, unibody or body-on-frame style vehicle frame ismanufactured in body-in-white production area 12. Body-in-whiteproduction area 12 feeds these bodies-in-white to paint area 14 wherevarious coatings (such as primers, colour coats, metallic coats, clearcoats, etc.) are applied to the body-in-white. These painted vehiclesare then transferred to storage assembly area 100—which comprisespainted body storage (PBS) area 100A (shown in FIG. 1A) and assemblybody storage area 100B (shown in FIG. 1B). After being processed instorage assembly area 100, vehicles are transferred to final assemblyarea 16. In final assembly area 16 a variety of operations are performedincluding, for example, installation of the interior trim, carpeting,instrument panel, seating, drive-train, fluids, etc.

[0038] Vehicles produced on assembly line 10 have at least one uniqueidentifier, typically the Vehicle Identification Number (VIN). Eachvehicle to be manufactured, as described above, has a build sheet, whichdescribes the processes to be performed on the vehicle and the locationsof those processes, and an assembly sheet identifying the parts to beinstalled on or to the vehicle. This information is stored in a computerdatabase (databases 208A, 208B of FIG. 2).

[0039] From information detailing the vehicles that need to bemanufactured (based on customer orders) a production schedule is set.This production schedule may be determined by inputting into a computer(such as server 206) the customer orders. The computer may thendetermine the parts required to build the vehicles ordered, determineparts availability for these vehicles, order more parts (if required),etc. Based on this information stored in the computer database, aproduction schedule is set. This production schedule groups likevehicles (that is those vehicles that have the same similar assembly andbuild sheets) into groups or lots. Each of the vehicle in the productionschedule will be assigned a unique identifier (such as, for example, aVIN) and a lot number. Each vehicle that is a member of the same lot ofvehicles will be assigned the same lot number. This information isstored in a database (such as database 208—FIG. 2). Moreover, eachvehicle has assigned three other pieces of data: a PBS status indicator;a lot condition indicator; and production status indicator, again, allstored in database 208. As described above, the PBS status indicator canbe set to either PASS or FAIL. As will be described below, the PBSstatus may be set by inputting information into a computer terminal orby an automated inspection device, such as a robotic panel gap measuringdevice which is in communication with database 208. The Lot ConditionIndicator can be set to DELAYED, CURRENT or FUTURE. The lot conditionindicator (hereinafter “lot condition”) can be set by central computer(such as server 206—FIG. 2) based on the production schedule, or basedon the status of the other vehicles in the same lot. Also associatedwith each vehicle is a production status indicator (hereinafter“production status”). A vehicle's production status condition can be setto SCRAP, HOLD or RELEASED. As noted above, the production statusindicates whether the vehicle is available to proceed to the nextmanufacturing process (i.e. RELEASED), the vehicle is temporarilyunavailable for further production (i.e., HOLD) or the vehicle has amajor defect and thus should be SCRAPPED.

[0040] Generally, FIGS. 1A and 1B illustrate a two level storageassembly area 100. Vehicles are received from the paint area 14 (FIG.1C) by storage assembly area 100 on lane 142 (FIG. 1B). Storage area 100provides an area for the inspection and, where possible, repair ofdefects on vehicles received, and the re-arrangement of vehicles priorto transfer to final assembly area 16 (FIG. 1C).

[0041] The goal of storage assembly area 100 is to transfer vehiclesreceived from Paint area 14 (FIG. 1C) to Final Assembly area 16 (FIG.1C) through storage assembly area 100 (FIGS. 1A, 1B, 1C) with a highpass lot rate of vehicles (that is, a high rate of vehicles with a PBSstatus of PASSED are to be transferred from storage area 100 to finalassembly 16). Moreover, storage area 100 is designed to re-arrange theorder of the vehicles prior to transfer to final assembly area 16 sothat vehicles with like lot numbers are, where possible, arranged toform a contiguous group. In this way, the number of parts changeoversrequired in Final Assembly area 16 is reduced. However, it must benoted, that, in order to ensure that final assembly area 16 does notexperience a shortage of vehicles from storage assembly area 100, it maysometimes be necessary to transfer vehicles in a particular lot to finalassembly area 16 that are not contiguously arranged.

[0042] The re-arrangement of vehicles in storage assembly area 100 isachieved by having a number of different routes between two points, theability to hold vehicles, the priority given to vehicles at variousswitching locations, and the overall co-ordination of these aspects. Asillustrated storage assembly area 100 is comprised of a plurality oflanes. These lanes, and other lanes incorporated in automobile assemblyline 10, include transport mechanisms such as, for example, conveyors(such as overhead conveyors, underbody conveyors, semi-autonomousrobotic vehicle carriers, manually transferred, vehicle carriers, or thelike) (hereinafter referred to generally and collectively as“conveyors”) to transport the vehicles (or painted bodies) throughstorage area 100. Each of these conveyors may be operated independentlyof the other conveyors. Further, it is not necessary that theseindependent conveying devices, such as the conveyors, be operated at thesame speed. In fact, as will be apparent below, it may be desirable tooperate some conveyors at a higher speed than others. Finally, as thelanes are operated independently, it is possible to prevent vehiclesfrom entering or leaving a lane. For example, lane 110E could beconverted to a permanent storage area by allowing vehicles to enter butpreventing vehicles from leaving. Similarly, if necessary, one of lanes110 could be shut down completely if required (e.g. for maintenancepurposes). Moreover, the conveyors, as will be described below, enablethe tracking of the position of each vehicle (in real-time) as it movesthrough assembly line 10, and more particularly, in storage assemblyarea 100. This tracking information is stored on database 208 ofmanufacturing network 200 (FIG. 2). The tracking of vehicles is assistedby the identification of vehicles (and updating of the computerdatabase) as each vehicles passes a Vehicle Identifiers (VIDs) 134. AVID 134 obtains, as a vehicle passes on the lane proximate the VID 134,the vehicle's identity and transmits this information (which may bedetermined, for example, by a VIN) via a communications link to database208.

[0043] Generally, a vehicle to be manufactured is tracked from the startof the manufacturing process to the time the vehicle is delivered to itsfinal destination. The tracking of a vehicle commences from the firstprocess in which a component or part is manufactured for a particularvehicle. This tracking may commence during the manufacture of thebody-in-white in body-in-white production area 12 (FIG. 1). In area 12,components are selected for welding of a particular portion of thebody-in-white (for example, the front engine room component of thebody-in-white) for a particular vehicle and its associated uniqueidentifier (its VIN, for example). From this moment onward, the vehiclewill be tracked by the movement of the vehicle by conveyors 216 (FIG.2). Conveyors 216 will, in association with PLCs 214, communicate andupdate database 208 so that database 208 maintains records as to theposition of the vehicle as it moves through assembly line 10. VIDs 134act as a backup and confirmatory device. To ensure that the recordsmaintained by database 208 regarding the position of the vehicles inassembly line 10, VIDs 134 identify vehicles as they pass proximate tothe position of the VIDs, which is then transmitted to database 208 sothat its records can be updated. VIDs 134 also operate to confirm theorder in which vehicles are placed on the various lanes. This is ofgreat assistance particularly where two or more lanes feed a singlelane.

[0044] It should be noted that a vehicle's position in assembly line 10can be determined directly—through the reading of a vehicle identifier,such as a SmartEye™ label, by a SmartEye™ reader, bar code reader, orother reader capable of identifying a particular vehicle (by thevehicle's VIN, for example)—or indirectly. A vehicle's position inassembly line 10 can be determined indirectly by associating thevehicle's unique identifier (such as, for example, a VIN) with a uniquevehicle carrier identifier that is transferred on a conveyor, such as aconveyor, through assembly line 10. The vehicle carrier, as noted above,may be for example, an overhead carrier, underbody carrier, or the like.The vehicle's identifier and the carrier identifier with which thevehicle is associated, may change over time if, and as, the vehicle ismoved from one carrier to another. This association between the uniquevehicle identifier and the carrier identifier could be stored indatabase 208 (FIG. 2). Conveyors of assembly line 10, such as conveyors,update database 208 with information as to the position of the carrierstransferred by the conveyor. This positional information of the vehiclecarriers may be gathered by having a plurality of check points, such as,for example, toggle switches or bar code readers, or the like, arrangedalong the route of the conveyor. As a vehicle carrier passes each checkpoint, a signal could be transmitted from the conveyor, through PLCs214, to database 208. Based on the check point passed by a vehiclecarrier, and previously stored information corresponding to previousvehicle position data acquired from previous signal received by database208, it can be determined, based on the fact that a specific vehicle isassociated with a specific vehicle carrier, the position of a vehicle ona particular conveyor. In an alternative embodiment, a conveyor couldtransmit to database 208 other operational information, instead of thetoggle switch information, from which the position of a vehicle could bedetermined. For example, a conveyor, such as a conveyor, could transmitto database 208 information corresponding to the conveyor's speed ofoperation. Based on this information, and the time elapsed since thelast update, the position of each vehicle carrier, and thus the vehiclecarried, could also be determined.

[0045] The lanes of storage assembly area 100 are arranged to intersectwith each other at a number of switching (or intersection) points. Basedon the overall status of vehicle (which includes, for example, its PBSstatus, its lot condition and production status), routing instructionsare generated and transmitted to the switching points so that a vehicleis transported according to a determined route. The switching points(indicated by a dot or circle on FIGS. 1A and 1B) may be, for example, arail conveyor switch, instructions to be performed by a semi-autonomousrobotic vehicle carrier, a robotic handler transferring a vehicle fromone lane to another, or the like. In the described embodiment theswitching points are controlled by a controller, such as computerapplication or sub-routine (referred to as a “processing station”), thatperforms operations upon an event occurring, such as a tracked vehiclearriving at a point proximate to a switching point. The controller ofthe switching points may be a computer application running on a computerproximate to the switching point, or as described below, it may becentralised a single machine such as, for example, server 206 (FIG. 2).A single processing station may co-ordinate the movement of vehicles bycontrolling several switching points. For example, processing station108 coordinates vehicles received from lane 102 and being transferred toone of five lanes (lanes 110A, 110B, 110C, 110D and 110E). Similarly,processing station 112 controls the movement of vehicles that are beingfed form lanes 110A-110E to lane 114. The controller may operate theconveyors of the lanes directly, or indirectly with the assistance ofProgrammable Logic Controller (PLC) or the like.

[0046] Generally, the conveyors, switching points and controller (suchas processing stations described below) form a router that routes avehicle through assembly line 10. The router determines, based oninformation about assembly line 10 and the vehicles thereon (such asequipment availability, vehicle manufacturing priority, availability ofconveyors, production schedules, status of various production areas(such as Final Assembly, Paint and the like), routing paths for eachindividual vehicle and routes these vehicles accordingly.

[0047] As aforementioned, the goal of storage area 100 is to re-arrangethe order of vehicles so that contiguous groups of vehicles with thesame lot number are transferred to final assembly area 16 (FIG. 1C). Themovement of vehicles to one of storage lanes 110 from lane 102(controlled by processing station 108) is based on the vehicle's PBSstatus, lot condition and production status. Similarly, vehicles aretransferred out of storage lanes 110, based on the same indicators, byprocessing station 112.

[0048] Generally, vehicles passed to storage assembly area 100 undergoan inspection process, the results of which are input into database 208via a computer terminal or by a robotic or automated inspection device.If a vehicle fails inspection its PBS status indicator may be set toFAIL. As a result, this vehicle may need to be repaired. Moreover, it ispossible that a single member of a vehicle lot may be the only vehicleto fail inspection. In such an instance, it is necessary for the failedvehicle to be repaired and prior to being sent to Final Assembly area 16(FIG. 1C). Further, it is desirable to have this failed vehicle, oncerepaired, be re-united with the other members of its vehicle lot. Thismay be accomplished by, for example, expediting the failed vehiclethrough storage lanes 110 into inspection and repair area 154. Ifpossible, any necessary repairs are carried out and the failed vehiclewill have its PBS status changed to PASSED. The repaired vehicle canthen be quickly moved, ultimately, to lane 174. Meanwhile, the othermembers of the repaired vehicle's lot may have been temporarily storedin storage lanes 110 or moved in the ordinary fashion to lane 118 andultimately to lane 174. By expediting the now repaired vehicle out oflanes 110, it is possible that this vehicle has “caught up” with theother members of its lot. If the repaired vehicle is still behind, orDELAYED, compared to other members of its vehicle lot, the repairedvehicle can be again expedited through storage assembly area 100 by theuse of shunt lane 180. The other members of its lot may have beendirected by the conveyor controller, processing station 178, to lane182. In this manner the repaired vehicle will have a much shorter routeto lane 186 (and ultimately final assembly area 16) than the othermembers of its lot. The repaired vehicle can then rejoin other membersof its lot at an appropriate position by having the computer activatethe conveyor in lane 180 at an appropriate time. In many cases, eitherof these two processes (expediting a FAILED vehicle from storage lanes110 and the use of shunt lane 180) will be sufficient to re-unite a lotof vehicles to form a contiguous group prior to final assembly area 186.

[0049]FIGS. 1A and 1B illustrate storage assembly line 100 embodying theinvention. In FIG. 1A, painted body storage area 100A illustrates thelower level of a two level storage assembly line 100. FIG. 1Billustrates the upper level of storage assembly line 100—the paintinspection, repair and ABS area 100B.

[0050] Referencing FIG. 1A, partially assembled vehicles (hereinafter,the term “vehicle” will be used to include those vehicles that arepartially and completely assembled), are received on lane 102 fromsecond repair and inspection area 150 proximate lane 12—of upper level100B (FIG. 1B). Lane 102 includes a conveyor that is communication withmanufacturing network 200 (FIG. 2, described in detail below). Theconveyor of lane 102 may be, for example, an overhead conveyor, anunderbody vehicle conveyor, an robotic vehicle transport device that canbe directed independently of other robotic transport devices, manualtransports, or the like. Located proximate to lane 102 is processingstation 104. Processing station 104, which interfaces with the conveyorof lane 102, either directly or via manufacturing network 200,simultaneously determines the position of vehicles on lanes 102 and 132.It should be noted that processing station 104 may only exist logically.That is processing station 104, and other processing stations describedbelow, may not have physical locations but may exist only logically, orvirtually, and may be, for example, computer applications orsub-routines running on computer server 206 or host computer 204 (FIG.2). Moreover, if required, and if processing stations exist onlylogically, the computer applications could be executed on differentcomputers. Based on the position of a vehicle (which can be determinedfrom the position of a vehicle carrier, or the vehicle itself on aconveyor, with this data being transmitted to, and updated in, database208) on the conveyor of lane 102 (or other lanes), manufacturing network200 (FIG. 2), determines the path that should be taken by a vehicle thatreaches the physical location demarcated by a processing station, suchas processing station 104. Hereinafter, the physical locations describedbelow and the operations of the processing stations described herein,may only be operations that are performed by the manufacturing networkupon certain events occurring, such as a vehicle arriving at thephysical area identified by the position of the processing stations.Based on the status of vehicles on lanes 102 and 132, processing station104 performs operations 300 (FIG. 3—described in detail below) to movethe identified vehicles from either lane 102 or lane 132 to lane 106.

[0051] Lane 106 feeds vehicles received from either lane 102 or lane 132into storage lanes 110A through 110E (collectively storage lanes 110).Proximate to lane 106 is processing station 108 and vehicle identifier(VID) 134A. Processing station 108, through the performance ofoperations 400 (FIG. 4) routes the vehicles from lane 106 into lanes110. VID 134A, which may for example, be a SmartEye™ or bar code reader,determines the identity of a particular vehicle entering an area. VID134A may use character, bar code or SmartEye™ code recognition, or thelike, for reading or scanning a Vehicle Identification Number (VIN) orother identifier which is unique to a particular vehicle. As thevehicles, which may be routed from lanes 102 or 132, past VID 134A theiridentity is determined and records, data and other information stored onthe database 208 of server 206 are updated via communication overmanufacturing network 200 (FIG. 2). The vehicles are then conveyed toone of storage lanes 10. A vehicle's position is also tracked bycontinuous updating of database 208 of manufacturing network 202 withpositional information received from conveyors 216 through PLCs 214(FIG. 2).

[0052] Storage lanes 110A-110E temporarily store vehicles until furtherprocessing is required or available. As will be described in more detailbelow, storage lanes 110A-110E are used to partially provide to themanufacturing system (which is combination of storage assembly line 100working in conjunction with, and controlled by, manufacturing network200) the ability to: re-arrange lots of vehicles; attempt to move anout-of-sequence vehicle which is preceded and/or followed by vehicles ofa different lot, back into sequence and to be re-united with the othermembers of the vehicle's original and proper lot.

[0053] At the head of storage lanes 110A-110E is processing station 112.Processing station 112 determines, based on the performance ofoperations 500 of FIG. 5 (and in conjunction with manufacturing network200), the order in which vehicles are removed from storage lanes110A-110E onto lane 114.

[0054] Lane 114 bifurcates into lanes 118 and 122. Proximate to the head(i.e., the most downstream position) of lane 114 is processing station116. Vehicles conveyed to lane 114 are passed from lane 114 to eitherlane 118 or loop lane 122 based on a determination made by processingstation 116. Processing station 116, in conjunction with manufacturingnetwork 200, determines based on the performance of operations 600 (FIG.6) and the status of the vehicle entering processing station 116, thelane to which the vehicle should be conveyed.

[0055] Lane 118 terminates at conveyor shifter 120 which moves vehiclesfrom painted body storage area 100A—the lower level of storage assemblyline 100—to the ABS area 100B—the upper level of storage assembly line100. Proximate to the lower level portion of conveyor shifter 120 isprocessing station 188 and VID 134B. VID 134B determines the identity ofvehicles passed to conveyor shifter 120. Processing station 188, throughoperations 1200 (FIG. 1200), controls the flow of vehicles into conveyorshifter 120.

[0056] Loop lane 122 conveys vehicles from lane 114 to lane 126. Alsofeeding vehicles to lane 126 are vehicles from lane 124. Vehicles fromlane 124 have passed through first vehicle repair and inspection area148 (FIG. 1B) are received from ABS area 100B (FIG. 1B). Proximate tolane 122 is VID 134C. Using the information gathered by VID 134C,processing station 136, in conjunction with manufacturing network 200through the performance of operations 700 (FIG. 7—described in greaterdetail below), controls the movement of vehicles to ensure thatcollisions are avoided between vehicles fed to lane 126. Moreover, theidentity, location and relative position of each vehicle on lane 126 isdetermined, and database 208 stored on server 206 is updated asrequired.

[0057] Lane 126 bifurcates at processing station 128 into spur lane 130and lane 132. Processing station 128, in conjunction with manufacturingnetwork 200, carries out the performance of operations 800 (FIG.8—described in greater detail below). Spur lane 130 is used to removevehicles, such as vehicles with a scrapped PBS status from storageassembly line 100.

[0058] Lane 132 itself bifurcates, with one portion leading to lane 152and the other returning to lane 102 via shunt lane 140. The path takenby a vehicle on lane 132 is determined by processing station 104 duringoperations 300 (FIG. 3—described in detail below).

[0059] Referencing FIG. 1B, paint inspection, repair and ABS area 100B,the upper level of storage assembly line 100, is illustrated. Vehiclestransferred from the Top Coat Paint Booth (not shown) are received atthe tail end lane 142. Proximate to the tail of lane 142 is VID 134Dwhich, as previously described, operates to identify the individualvehicles as they are routed past VID 134D. Downstream of VID 134D onlane 142 is inspection and repair area 148. Inspection area 148 throughoperations 1500, shown in FIG. 15 and as will be more thoroughlydescribed later, accesses the records for a vehicle entering area 148,identifies, through inspection, any defects or faults in these vehicles.The inspection, which may be carried out in-line or off-line, may beperformed manually (i.e., by an associate, or through automation. Thisinspection information for a particular vehicle is then transmitted toand stored in the database 208 hosted by server 206. The defectsidentified at inspection area 148 may then be repaired at a downstreamstation. Downstream of inspection and repair area 148 is an intersectionwhere lane 172 merges with lane 142. Proximate to this merging point isVID 134E. (Lane 172 as well as lanes 158, 162 and 170 are manualtransfer lanes (i.e. lanes which are not automated but controlled byassociates), denoted by the thicker line widths in FIG. 1B. Although, ifdesirable, lanes 172, 162, 158 and 170 may be automated). Furtherdownstream of VID 134E on lane 142 is second inspection and repair area150. As before, area 150 is designed, for each vehicle passing through,to identify any defects, transmit data corresponding to defectsidentified to computer server 206, access the records stored by computerserver 206 for the identified defects for, the particular vehicle,perform possible repairs, and transmit information corresponding tothese repairs to computer server 206 so that its records are updated. Itshould be noted that repair area 150, like repair area 154, may not havethe capability to repair a particular defect for a particular vehicle.Vehicles leaving second inspection and repair area 150 are thenultimately conveyed to lane 102 (FIG. 1A).

[0060] Vehicles are also received at ABS area 100B of storage assemblyline 100 through the conveyance of vehicles from lane 138 (FIG. 1A) tolane 152 (FIG. 1B). Lane 152 conveys vehicles through third inspectionand repair area 154 to processing station 188. Inspection and repairarea 154, manually and/or through automation, further identifies anydefects in received vehicles, logs the identified defects with computerserver 206, performs repairs where possible (depending on the timeavailable, nature of the defect and tools available, etc.), and recordsany performed repairs with computer server 206. Downstream of thirdinspection and repair area 154 on lane 152 is VID 134F. VID 134Fidentifies vehicles conveyed passed its position. Further downstream ofVID 134F on lane 152 is processing station 156. Based on the status ofthe vehicles arriving at processing station 156 (the operations of whichare described below with reference to FIG. 9), the vehicle will beconveyed to either of lane 158 or lane 162. Lane 162 ultimately feedsvehicles back to lane 142 at the merging point proximate to VID 134E oflane 142 via transfer lane 172. Vehicles conveyed to lane 158 will beconveyed to processing station 166 located proximate to the head of lane158. Processing station 160 (the operations of which are described indetail below, with reference to FIG. 10), determines whether, based on,amongst others, the overall status and position of the vehicle, whetherto transfer the vehicle to lane 172 or lane 164. Vehicles transferred tolane 172 will ultimately merge with lane 142. Vehicles transferred tolane 164 will be conveyed to processing station 166 located proximate tothe head of lane 164. Processing station 166 (through the performance ofoperations 1100—FIG. 11) instructs the conveyors to convey an arrivingvehicle to either lane 170 or lane 168. A vehicle conveyed to lane 170,which merges with lane 146, will be conveyed to lane 124 (FIG. 1A). Avehicle conveyed to lane 168 will pass to processing station 188.Processing station 188 controls (through the performance of operations1200—FIG. 12) the movement of vehicles from Painted Body Storage area100A (FIG. 1A), lane 168 and into ABS lane 174.

[0061] Vehicles conveyed to lane 174 will pass VID 134H, which, asdescribed above, transmits information, including vehicle identity andlocation, to computer server 206 (FIG. 2). Downstream of VID 134H onlane 174 is EcoWrap™ area 176 where a protective film is applied toportions of the painted vehicle body. Upon exiting EcoWrap™ area 176, avehicle is conveyed to processing station 178 which is located proximateto the head of lane 174 and the tail of lanes 180 and 182. Processingstation 178, through the performance of operations 1300 (FIG. 13 anddescribed below in detail) controls movements between lane 174 and lane186. Lane 180 shunts vehicles from lane 174 to lane 186. Lane 182 isalso connected between lane 174 and lane 186 but, through its circuitousrouting provides temporary vehicle storage, enabling further vehiclerearrangement, and therefore lot control. Spur lane 190, which splitsfrom lane 182, provides for the manual removal of empty vehiclecarriers, if such a conveyor system is used. Proximate to the heads oflanes 180 and 182 and the tail of lane 186 is processing station 184 andVID 1341. As will be described below, processing station 184 performsoperations (operations 1400, FIG. 14) to control the movement ofvehicles from lanes 180 and 182 to lane 186. As will now be apparent,VID 1341, proximate to lane 184, identifies the identity and order ofthe vehicles conveyed on lane 186, updating the records of the database208 on computer server 206 accordingly. Lane 186 conveys vehicles tofinal assembly.

[0062] Referencing FIG. 2, manufacturing network 200 is comprised of anetwork backbone 202, which provides for communication and may be, forinstance, provided by known physical wiring technologies, such as10BaseT, 100BaseT or the like, or wireless communications services andknown networking communications standards such as, for example,Ethernet, token ring or TCP/IP networks. As illustrated, connected tonetwork backbone 202 is host computer 204, network or computer server206, plant signage 207, printers 210, terminals 212 and ProgrammableLogic Controllers (PLCs) 214. Connected to PLCs 214 is manufacturingequipment 216 which includes, but is not limited to, readers (such VIDs134A-I, hereinafter collectively VIDs 134), robots (welding, VINstamping, painting, sealers, surfacers, fluid fillers, engine placer,quality testing equipment, glass placement, and the like), conveyors,vehicle carriers, torque guns, computer terminals for data input andoutput, repair and inspection robots, and the like. PLCs 214 aretypically assigned a unique address, such as IP address or the like. Asa result, the addition of new pieces of equipment can be easilyfacilitated by inserting a new PLC 214 into network 200 and attachingthe equipment to the new PLC.

[0063] Computer medium 205, which contains instructions for server 206,is readable by server 206. Computer medium 205 may contain, for example,database software, computer applications (including, for example,sub-routines corresponding to processing stations 104, 108, 112, 116,188, 136, 128, 156, 160, 166, 178 and 184; and inspection areas 148, 150and 154), computer data, network software, data corresponding to thelayout of assembly line 10 (FIG. 1C), or the like. While computer medium205 is illustrated as a computer diskette, it could equally be a tape,memory chip, or other removable or non-removable computer readablemedium. Furthermore, the software medium may be a remote medium, such asa memory of a remote computer, and be downloaded over a suitable linksuch as over an network, internet, intranet, dedicated data link, or thelike.

[0064] Data collected from VIDs 134, such as a SmartEye™ reader, whichincludes the vehicle identity (VIN) and vehicle location, is transmittedfrom the reader, which may be connected to a PLC 214 over networkbackbone 202 and stored in database 208A running on server 206. Aredundant database, database 208B, is stored and housed by computerserver 206. Database 208A stores data about a particular vehicle thatcorresponds to conventional build instruction data, as well as enhanceddata corresponding to each vehicle's progress through the manufacturingprocess including: identified defects, PBS status, lot number, repairsperformed, repairs required, physical position on storage assembly line100 as measure over time, carrier identification upon which a vehicle istransported throughout a plant (which may change over time),identification of individual components installed on the vehicle,installation instructions performed during assembly (such as, forexample, the torque settings used to install lug nuts, bolts, etc.), andthe like. Virtually every part, every process and every repair andinspection detail associated with the manufacturing process and thevehicles manufactured is stored in databases 208A, 208B. In addition tothe above noted data that is keyed to specific vehicles, general datacorresponding to the assembly process as a whole is also stored indatabase 208A on host 206. This general assembly process data includes:inventory data, production schedules, tool (including robot)availability, quality results and the like. In an embodiment of theinvention, database 208A is used for the collection of production data,and determines routing of vehicles throughout the manufacturing process,while database 208B is a replication of database 208B that is used fornon-production inquiries (such as those made by management and suppliersabout production status) and backup purposes. Using database 208A solelyfor manufacturing purposes assists the system's response time todatabase access by limiting non-production inquires and access toredundant database 208B. Database 208B may be updated every few secondsor minutes, as required. In the event that database 208A fails,production access could automatically be transferred to database 208Buntil such time as database 208A is operating normally. Databases 208A,208B may be commercially available software such IBM™ UniversalDatabase™ (UDB), Oracle™ database, or the like. Hereinafter, databases208A and 208B will be referred to interchangeably and collectively asdatabase 208.

[0065] PLCs 214, which may be those commercially available fromsuppliers such as Yaskawa™, Mitsubishi™, Allen Bradley™, and others,enable the communication between the various pieces of manufacturingequipment 216, to enable data to be transmitted from equipment 216 overnetwork backbone 202 to server 206, and vice versa. Consequently, PLCs214 enable two way transmission of data, including electronicinstructions, to/from the equipment from/to the host computers. As aresult, counter-measures to adjust the production process, such as newrobotic build instructions (which may be in the form of ladder logicinstructions) can be transmitted from computer server 206 to the variouspieces of manufacturing equipment 216. Similarly, data on theperformance of equipment 216, such as operations performed, equipmentavailability and the like can be transmitted from equipment 216, throughPLCs 214 over network backbone 202 to computer server 206.

[0066] Terminals 212 enable real-time input and output of data from lineworkers (also referred to as associates), management and otherinterested parties. For example, data corresponding to defectsidentified or repairs performed by an associate relating to a specificvehicle may be input into terminals 212 by use of input device, such askeyboard, touch screen, bar code reader, or the like. This informationwould then be available to any other terminal or networked device (suchas plant signage 207) for the display of data. The data so displayed maybe summarised or collated by computer server 206 in a variety ways thatare known. A network, such as network 202, does not have to bephysically located on a single site. That is, network 202, althoughillustrated as a Local Area Network (LAN) may also be part of a WideArea Network (WAN). In an embodiment of the invention, terminals 212would be available: at a number of physical locations throughout themanufacturing plant; at other plants of the manufacturing; at offices ofthe manufacturing; at the suppliers plants and offices; and others (suchas sales dealers, warehouses, etc.). These terminals 212 would be incommunication with database 208 via a wide area network (which may beprovided through, for example, a dedicated connection, a virtual privateconnection, or via a public network, such as the Public SwitchedTelephone Network (PSTN) or the Internet). Terminals 212 may access thedata on database 208 through custom software or via commercial softwaresuch as web-browsers, such as Internet Explorer™ or Netscape™Navigator™.

[0067] Server 206 monitors and controls manufacturing network 200. Also,as indicated previously, server 206 hosts database 208A. Server 206 maybe a conventional work station, such as an IBM™ RS/6000™ running AIX™.Server 206 may also provide for data archiving and redundant capacityshould there be a failure in server 206, and vice versa. If required,server 206 may be several individual computers providing thefunctionality described herein.

[0068] Printers 210 may be distributed throughout the manufacturingplant and may provide for the printing of: ID Cards; tracking sheets;assembly sheets for the body, frame, instrument panel, engine, knuckles,and inspections cards; and inventory print-outs, and the like.

[0069] Referencing FIGS. 1A, 2 and 3, operations 300 are performed whena vehicle reaches processing station 104, proximate to lanes 102 and138. The determination of whether a vehicle has reached processingstation 104 is determined by server 206 accessing the records ofdatabase 208, which, as previously described, receives and maintainsdata which tracks every vehicle's position in assembly line 10,generally, and storage assembly line 100, specifically. This positionaldetermination is continuously performed by server 206 for operations 300and the other operations 400-1500. Hereinafter, as operations 300-1500are and the positional determinations (i.e., determining when vehiclesare proximate to a processing station) are both performed on server 206,reference will be made to the processing stations as making thispositional determination for ease of understanding. Operations 300manage the movement of vehicles from lane 132 to the repair area 154 vialane 152 (FIG. 1B) or to lane 106 (via shunt lane 140) and from lane 102to lane 106. Processing station 104 ensures that possible collisionsbetween vehicles to be moved to lane 106 from both lanes 102 and 132 areavoided. Moreover, processing station 104 can enable simultaneoustransfer of one vehicle from lane 132 to lane 138 and a second vehiclefrom lane 102 to lane 106.

[0070] If it is determined by processing station 104 that there isvehicle at the head of lane 132 (S302) that has a “failed” PBS status(S304), then the vehicle is passed to lane 138 (S306) so that it may berepaired at repair station 154 (FIG. 1B). The determinations made byprocessing station 104 in steps S302, S304 are accomplished by accessingthe database 208 stored in computer server 206 to determine if there isa vehicle carrier proximate to processing station 104, if so, theidentify and PBS status of the vehicle it is carrying is alsodetermined. This query is transmitted from processing station 104(which, as described above, may only exist virtually and may be, forexample, a computer application running on computer server 206 or hostcomputer 204) to computer server 206 over network backbone 202. Theresponse to this query, which may, for example, be based on structuredquery language (SQL) or other database 208 accessing instructions, istransmitted back to processing station 104. Based on the query response,processing station 104 transmits instructions to the conveyor(s) 216,again over network backbone 202, and via a PLC 214 interfacing with theconveyor(s) 216.

[0071] If processing station 104 determines that there is vehicle at thehead of lane 132, and this vehicle has a “failed” PBS status, then thevehicle is transferred to lane 138 (S306). If a vehicle located at thehead of lane 132 has a different PBS status (that is, PASSED), theconveyors and switches between lanes 132 and 140 and lanes 140 and 102are instructed to transfer the vehicle from lane 132 to lane 106 viashunt lane 140 (S308). If there is not a vehicle at the head of lane132, or there was a vehicle that was handled by steps S306 or S308,processing station 104 determines, in S310, if there is a vehicle at thehead of lane 102. If there is not a vehicle at the head of lane 102,again determined based on vehicle carrier position and the status ofthat particular carrier (i.e., is the carrier carrying a vehicle, and ifso, which vehicle), operations 300 cease until processing station 104determines that a vehicle is at the head of lanes 132 or 102. If it isdetermined by processing station 104 that a vehicle is located at thehead of lane 102 (S310), this vehicle is transferred, again byinstructions transmitted by processing station 104, via network backbone202, and through PLCs 214, by the conveyors 216 (and the switch betweenlane 102 and lane 106) to lane 106 (S312).

[0072] Operations 400 which are illustrated in flow chart form in FIG.4, are performed by processing station 108 for the loading of storagelanes 110. If it is determined (in the manner described above—i.e.,through interaction of the processing station, computer server 206,network backbone 202 and PLCs 214 in communication with the conveyor(s)216) that a vehicle on lane 106 has a production status of HOLD or SCRAP(S402), the vehicle is transferred, by operation of the conveyor(s), tolane 110 with: the most HOLD or SCRAP vehicles; or the emptiest lane 110(S404). If there is a tie (that is, there is at least one empty lane andat least one lane with a HOLD or SCRAP vehicle, or many lanes that areempty, or many lanes with the same number of HOLD or SCRAP vehicles, thepriority of processing station 108 is to load the highest alphanumericnumbered lane (i.e. lane 110E prior to lane 110D). If the vehicle passedto lane 106 has a production status different from HOLD or SCRAP (S406)(i.e. RELEASED) and the vehicles has a PBS status of FAILED, thenvehicle is transferred to the emptiest storage lane 110 (S408). In theevent of a tie with respect to the emptiest storage lane (i.e., morethan one lane of lanes 110 is empty), priority again goes to the highestalphanumeric number line. If the PBS status of the vehicle is PASSED(S406), then it is determined whether there are vehicles of the same lotin lanes 110 (S410). This determination is made by accessing thedatabase 208 on server 206, determining the to-be-transferred vehicle'slot number, accessing the database 208 to determine if there are anyvehicles in storage lanes 110, if so, determining those vehicle's lotnumbers. If it is determined that there are other vehicles in storagelanes 110 with the same lot number as the to-be-transferred vehicle(S410), the vehicle is transferred to lane 110 with the highest numberof vehicles with the same lot number as the to-be-transferred vehicle(S412). A tie results in the transfer of the car to the lowestalphanumeric lane available. If there are no vehicles in storage lanes110 with the same lot number as the to-be-transferred vehicle, thevehicle is transferred to the emptiest storage lane 110. Again, in theevent of more than one empty lane, the vehicle will be transferred tolowest alphanumeric lane. This latter determination (i.e., determiningwhether there are stored vehicles with the same lot number as theto-be-stored vehicle) can be accomplished by processing station 112, inS412, accessing database 208 to determine the lot numbers of thevehicles currently stored in storage lane 110 and comparing those lotnumbers to that of the vehicle to be transferred to storage lanes 110.If there are vehicles in storage lanes 110 that have the same lot numberas the vehicle in lane 106, the vehicle in lane 106 will be moved to astorage lane 110 having vehicles with the same lot number, if possible.As will now be apparent, the provision of storage lanes 110 and theperformance of the above-described operations 400 enable therearrangement of vehicles fed to storage lanes 110 by lane 106.

[0073] Vehicles are only temporarily stored in storage lanes 110.Simultaneous to the performance of operations illustrated in FIGS. 3-14,operations 500 (FIG. 5) are being performed by processing station 112which is proximate to the head of storage lanes 110. Operations 500 aredesigned to sort the vehicles in storage lanes 110 and move thesevehicles back into the various assembly processes. Operations 500 aredesigned to move scrap or hold vehicles at the head of one of thestorage lanes which also has at least one released vehicles behind it,to be moved into lane 114 in an effort to allow the released vehicles tobe, ultimately, transferred to lane 118. The hold or scrap vehicles willthen automatically get shunted, or transferred, back into storage lanes110 via lanes 122, 126, 132, 140 and 106. Further, operations 500 aredesigned so that vehicles, having a PASSED PBS status, are delivered toABS area 100B (FIG. 1B) as quickly as possible while maintaining a highlot pass rate (i.e. a high number of vehicles with a PASSED PBS statusbeing transferred to final assembly area 16 (FIG. 1C). As illustrated inFIG. 5, processing station 112 determines if there is a released vehicle(i.e., a vehicle that is neither on HOLD nor SCRAP) with a FAILED PBSstatus at the head of one of storage lanes 110 (S502). If there is areleased vehicle at the head of one of the storage lanes 110, then thevehicle is transferred to lane 114 (S504). If there is a tie (i.e. morethan one lane has a RELEASED vehicle at its head) priority goes to thelane with a vehicle with a lot condition of DELAYED and/or the lowestalphanumeric number. If there is not such a vehicle, a furtherdetermination is made by processing station 112 to determine if anon-released vehicle is at the head of one of storage lanes 110 that hasat least one released vehicle in same lane (S504). If such a conditionexists (non-released vehicle at head of lane 110, with a releasedvehicle in the same lane), the non-released vehicle is passed to lane114 (S504). If neither of the conditions of S502, S506 are satisfied,processing station 112 determines if there is a released vehicle, whichhas a passed PBS status at the head of one of the storage lanes 110(S508, S514, S516). If such a vehicle is at the head of one of storagelanes 110, then the vehicle's lot condition determines if it istransferred. For vehicles with a “passed” PBS status and having adelayed lot condition, processing station will move the oldest (that isthe vehicle that is further behind the other members of its assignedlot) delayed lot condition (S510) to lane 114 (S504). In this way, thevehicles that are most out-of-synchronisation with other members of itslot, are given a priority with the desire that the vehicle be re-unitedwith its other lot members. If no delayed, passed and released vehiclesare currently at the head of a storage lane, a released and passedvehicle at the head of storage lot with a lot condition of “current”,will be transferred to lane 114 (S504). Finally, any vehicles that havea PBS passed status, that are released, have a lot condition of “future”and are located at the head of a storage lane 110 (S516) will betransferred to lane 114 (S512). Priority is given to oldest of those“future” lot condition vehicles (S518) should there be multiples of suchvehicles at the head of storage lanes 110.

[0074] Accordingly, operations 400 and 500 enable a vehicle with adelayed lot condition and a passed PBS status can be quickly routed infront of other vehicles with a current or future lot condition, or havea different PBS status. Consequently, storage lanes 110 enable vehicleswith the same lot number to move towards the remaining processes, suchas those performed during Final Assembly, more quickly than othervehicles. Therefore, storage lots 110, through the various operationsperformed by the various processing stations, including operations 400by processing station 108 and operations 500 of processing station 112,may be sufficient to enable a vehicle that has been found to have adefect which has been subsequently repaired, to be reunited with theother members of its lot.

[0075] Referencing FIGS. 6, 1A and 2, operations 600 are performed byprocessing station 116. Operations 600 are designed to control themovement of vehicles from lane 114 to either lane 118 or lane 122. If avehicle at the head of lane 114 (determined by communication overmanufacturing network 200 between processing station 116, computerserver 206, and conveyors 216 via PLCs 214 over network backbone 202)has a “passed” PBS status (S602), the vehicle will be transferred byconveyors 216 to lane 118 (S604). Vehicles passed to lane 118 will beidentified by VID 134B which is proximate conveyor shifter 120. Asdescribed above, VID 134B obtains a vehicle's identity passing proximateto VID 134B and transmits this information for storage in the database208 hosted by server 206 (S608). However, a vehicle at the head of lane114 with a PBS status other than “passed” will be, instead, transferredto loop lane 122. Vehicles passed to loop lane 122 may ultimately beremoved from the manufacturing process via spur lane 130, transferredback to storage lanes 110 (via lanes 126, 132, 140 and 106) or betransferred for repair and inspection area 154 (conveyed via lanes 126,132, 138 and 152).

[0076] Operations 700 illustrated in FIG. 7, are performed by processingstation 136, which is proximate the heads of lanes 122 and 124.Processing station 136, through the performance of operations 700controls the movement of vehicles from loop lane 122 and lane 124 (whichhave been transferred from lane 146—FIG. 1B). If it is determined that avehicle is at the head of lane 122 (S702), then that vehicle is moved tolane 126 (S704). If it is then determined that there is a vehicle at thehead of lane 124 (S706), then this vehicle is also conveyed to lane 126(S708) in a manner like that described above (through communicationbetween processing station 136, PLCs 214 and conveyors 216 overmanufacturing network 200). By performing operations S702 and S706serially, possible collisions between vehicles from lanes 122 and 124are avoided. Vehicles conveyed to lane 126 pass by VID 134C whichtransmits data to host 202 including the vehicle's identities, position,etc. (S710).

[0077] Operations 800, illustrated in FIG. 8, are performed byprocessing station 128 located at the head of lane 126 and prior to spurlane 130. If a vehicle or vehicle carrier proximate processing station128 needs to be removed from the manufacturing system (S802), asdetermined by processing station 128, the vehicle is transferred to spurlane 130 (S804). Otherwise, the vehicle is automatically transferred tolane 132 (S806).

[0078] As described above, vehicles from Top Coat Paint Booth aretransferred to lane 142. These vehicles are identified by VID 134Dproximate to lane 142 and are tracked in the usual manner. Vehiclesentering lane 142 pass through inspection area 148. In inspection area148, as described above, the vehicle is inspected (either manuallyand/or through automation) for defects and the vehicle's PBS status willbe set accordingly. If the vehicle has failed inspection at inspectionarea 148 and is either a current or future lot vehicle, the vehicle istransferred to lane 146 and ultimately to lanes 110 for temporarystorage. If the vehicle fails inspection and the vehicle has a delayedlot condition status, the vehicle will be transferred to inspection andrepair area 150 via lane 142 so that the vehicle can be repaired andultimately, re-united with the other members of its lot. If all repairsidentified for a particular vehicle at area 150 are effected, then thevehicle's PBS status is set to PASS. Regardless of whether all therepairs are effected at area 150, delayed lot vehicles will be passed tolane 102 via lane 142.

[0079] Referencing FIGS. 9 and 1B, operations 900 are performed byprocessing station 156 proximate to the head of lane 152. The PBS statusof the vehicle inspected at third inspection and repair area 154 is setto either “pass” or “fail” either through automated inspection orthrough receipt of data input at a terminal 212 of manufacturing network200 (S902). If processing station 156 the vehicle's PBS status is set to“fail” (S904), then the vehicle will ultimately be moved into a repairarea via lanes 158, 162 or 172 and 146. However, should the vehicle havea “passed” PBS status, processing station 156 determines whether thevehicle proximate to this processing station has a lot which, comparedto those vehicles in lanes 168, 174 and 182, is delayed (S908). If it isdetermined that the vehicle at processing station 156 has acomparatively delayed lot (i.e., the vehicle's is delayed more thanthose vehicles at lanes 168, 174 or 182), then the vehicle isprioritised by transferring the vehicle to lane 168 (S910). In thismanner, and with the assistance of lanes 180 and 182, controlled byprocessing station 178, this delayed lot vehicle is moved more quicklythrough the lanes of storage assembly line 100 in attempt to re-unitethis delayed vehicle with other members of its lot.

[0080] Should the vehicle at processing station 156 be a member of thecurrent lot (S912), the vehicle is moved to lane 172 (S914). Similarly,a vehicle that is a member of a future lot (S916) will be transferred tolane 162 (S918). Vehicles with a lot condition of CURRENT or FUTURE aremoved into lanes 162 or 172 so that they may ultimately be moved intostorage lanes 110 allowing DELAYED vehicles (with a PBS status ofPASSED) to move ahead of these vehicles prior to lane 174.

[0081] Processing station 160, proximate to the head of lane 158,performs operations 1000 and simply acts as a monitoring stationdetecting the movement of vehicles and updating the database 208 on hostcomputer 204 as required (S1002).

[0082] Similarly, processing station 166, proximate to the head of lane164, performs operations 1100 and simply acts as a monitoring stationdetecting the movement of vehicles and updating the database 208 on hostcomputer 202 as required (S1102). Processing station 166 also acts as agatekeeper by sounding a warning should an erroneous attempt be made totransfer a vehicle with a “failed” PBS status to lane 168.

[0083] Processing station 188 performs operations 1200 (FIG. 12) tocontrol movement of vehicles from lanes 118 (FIG. 1A) and 168 (FIG. 1B)into lane 174 (which is also known as the Paint Off process area).Processing station 188 attempts to maintain a high lot pass rate. Ifprocessing station determines that the arriving vehicle from either lane118 or lane 168 is a member of delayed, current or future lot, then oneof the vehicles will be transferred to lane 174. Priority between thetwo lanes 118 and 168 is given to the vehicle with the comparativelyolder lot. That is, a lane with a vehicle that is a member of a delayedlot will have priority over a vehicle in the other lane (of lanes 118and 168) that is a member of a current lot or a future lot. Similarly,priority is given, by processing station 188, to those vehicles thathave a current lot over those with a future lot (S1202). If there is nolot difference between the vehicle arriving at processing station 188from lane 118 compared to that arriving from lane 168 (S1204), thenpriority is given to the vehicle from lane 168 (S1206) in an attempt toprevent the inspection and repair areas 148, 150, 154 from becomingbacklogged.

[0084] Processing station 178, proximate to the head of lane 174 and thetail of lanes 180 and 182 controls the movement of vehicles between lane174 and shunt lane 180 or storage lane 182. The normal sequence is forcurrent lot vehicles to be moved from lane 174 to lane 182. However, ifit is determined by processing station 178 that the vehicle arrivingfrom lane 174 is comparatively delayed compared to the vehicle at thetail of lane 182 (S1302), then the lane 174 vehicle is shunted (therebyjumping the queue of vehicles in lane 182) to shunt lane 180 (S1304). Inthis manner, delayed vehicles are prioritised and an attempt is made tomove the vehicle downstream more quickly in an attempt to re-unite thedelayed vehicle with other members of its assigned lot. If the vehiclearriving at processing station 178 from lane 174 is a future or currentlot member compared to vehicle at the tail of lane 182, then the vehicleis moved via shunt lane 180 (S1304). Otherwise, and as aforementioned,other vehicles (CURRENT or FUTURE lot vehicles) are moved to storagelane 182 (S1306). Finally, processing station 178 also controls themovement of empty vehicle carriers into lane 190 (S1308).

[0085] Operations 1400, performed by processing station 184, aredesigned to control the movement of vehicles into lane 186 (whichultimately leads to final assembly) and thus, may be the last chance toalter the sequence of vehicles prior to final assembly. Processingstation 114 moves vehicles from lanes 180 and lane 182 onto lane 186 inthe order of delayed lot, current lot and then future lot (S1402).

[0086] Operations 1500, illustrated in FIG. 15, are performed by repairarea 148. As before, operations 1500 are performed by server 206 (FIG.2) upon the occurrence of an event, namely the exiting of a vehicle fromrepair area 148. A vehicle entering repair area 148 (from Paint area 12)is inspected for defects. Any defects identified are transmitted toserver 206 and database 208 is updated accordingly. The defects may beentered via a computer terminal 212 or by automated inspectionequipment, such a panel gap laser measuring device. If the vehicle haspassed inspection (S1502), the vehicle is transferred to lane 142(S1504). If the vehicle has failed an inspection (S1502), the vehicle'sPBS status is set to FAIL (1506). A determination is then made, based onthe vehicle's priority (i.e. it is a released vehicle with either aDELAYED or CURRENT lot condition) and the availability of space atrepair areas 150 and 154, on the routing of the vehicle (S1508). If thevehicle does not have priority and there is no space available thevehicle is transferred to lane 146 (S1510). If space is available andthe vehicle has priority, the vehicle is expedited to repair bytransferring the vehicle to lane 142 (S1504).

[0087] As will now be apparent the re-arrangement of members of vehiclelot, due to some of those members having to be repaired, or members of adifferent lot being inserted into the lot after being repaired, can bere-routed by the various operations increasing the likelihood thatvehicles having the same lot are processed contiguously during FinalAssembly, and other processes. This increase in contiguous processinglimits the number of changeovers that are necessary at the variousdownstream workstations.

[0088] Moreover, as the build instructions for each vehicle are storedelectronically, these instructions, if necessary, can be altered while avehicle is on the assembly line. For example, if it is determined,either by computer server 206, or the operators of the manufacturingsystem, that the production targets are not being satisfied for aparticular type of vehicle, for instance vehicles with a luxury orupgraded sound system, the build instructions for lots upstream (thatis, earlier in the manufacturing process) may be altered “on-the-fly”,or in real time. For instance, the vehicles in the lots behind the lotswith upgraded sound systems originally may have included a buildinstruction to install an economy sound system. By altering the buildinstruction records of those vehicles, which are stored in computerserver 206, these later lots of vehicles may be changed mid-process tohave luxury sound systems installed. Similarly, if it is determined thatsome parts are delayed (i.e., storage assembly line 100 is experiencinga parts shortage), the build instructions from some of the vehiclescurrently on storage assembly line 100 may be altered so that loss ofproduction is reduced. Similarly, those vehicles that are currently onstorage assembly line 100, that absolutely require the delayed parts maybe placed in temporary storage (on lanes 110) so that other vehicleswhich can be completed with the inventory of parts on-hand can beprioritised. As the information is stored in a database 208 accessibleon the plant floor, in the offices of management, and available tosuppliers (inside the company or outside), changes in the buildinstructions to a single vehicle results in this information beingavailable throughout the entire manufacturing process (that is, from thesuppliers of raw materials, to suppliers of components, to other plants,through to the factory floor). Moreover, the system described herein, ifrequired, can broadcast these changes to a variety of parties, such as,for example, suppliers, so that the necessary inventory to satisfy thebuild alterations is available and ready on the manufacturing floor whenthe vehicle is transferred to the various manufacturing stations.

[0089] From the foregoing, it will be apparent to those skilled in theart the embodiment and invention described herein increase theefficiency of the operation and smoothes production of assemblies, suchas an automobile. That is, the invention when applied to an assemblyline may reduce: parts changeovers; downtime due to paint flushingrequirements; assembly line stoppages due to parts shortages; and thelike.

[0090] Moreover, the above described system, particularly the numerouslanes (including storage lanes, shunt lanes, and conventional lanes) andthe numerous interchanges and merge points between the conveyorscontrolled by server 206, enables a multitude of routing paths betweentwo points to be created. This multitude of routing paths between twopoints enables a delayed vehicle to bypass other vehicles that areinterposed between the delayed vehicle and other vehicles of the samelot, or group, as the delayed vehicle.

[0091] While the embodiment of the invention described herein isdescribed as being applied to the painted body storage area and assemblybody storage area, both of which precede final assembly, the instantinvention can also be applied to the other portions of the assemblyprocess such as, for example, paint area 14, final assembly area 16 andthe manufacture of the body-in-white area 12 (FIG. 1C). The inventioncould also be applied to the inventory control system for providingparts at line side.

[0092] While one (or more) embodiment(s) of this invention has beenillustrated in the accompanying drawings and described above, it will beevident to those skilled in the art that changes and modifications maybe made therein without departing from the essence of this invention.All such modifications or variations are believed to be within thesphere and scope of the invention as defined by the claims appendedhereto.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. An assembly line for processing assemblies, said assembles formed into lots, and each lot having a manufacturing priority, said assembly line comprising: a plurality of conveyors to move said assemblies from a first point to a second point; a plurality of switching points interconnecting said plurality of conveyors to form a plurality of paths from said first point to said second point; a controller for controlling said plurality of switching points such that a lot of assemblies reaches said second point according to the manufacturing priority of said lot and such that said assemblies of said lot are substantially contiguous upon reaching said second point.
 2. The assembly line of claim 1 wherein said controller is also for controlling said plurality of conveyors.
 3. The assembly line of claim 2 wherein said controller is in communication with said plurality of conveyors and said plurality of switching points and is adapted to determine a routing path for directing said assemblies of said lot along one of said plurality of paths between said first point and said second point.
 4. The assembly line of claim 1 further comprising an assembly identifier for obtaining assembly identity information for a given assembly on a first conveyor of said plurality of conveyors, as said given assembly passes said assembly identifier, and transmitting said assembly identity information to said controller.
 5. The assembly line of claim 4 wherein said assembly identifier comprises an optical reader.
 6. The assembly line of claim 5 wherein said optical reader comprises a bar code reader.
 7. The assembly line of claim 4 wherein said first conveyor is operable to transmit information relating to said first conveyor speed to said controller.
 8. The assembly line of claim 7 wherein said controller is operable to track a location for said given assembly upon receipt of said assembly identity information and said first conveyor speed information.
 9. The assembly line of claim 1 wherein said controller is for controlling such that a first lot of assemblies having a lower priority than a second lot of assemblies is delayed with respect to said second lot assemblies.
 10. The assembly line of claim 9 wherein said controller is for controlling such that any separated assembly of said second lot by-passes intervening assemblies of other lots to rejoin said second lot.
 11. The assembly line of claim 1 wherein said assemblies are automotive assemblies.
 12. A method of operating an assembly line, where said assembly line includes a plurality of conveyors to move assemblies from a first point to a second point and a plurality of switching points interconnecting said plurality of conveyors to form a plurality of paths from said first point to said second point, said method comprising: determining a manufacturing priority of a lot of assemblies; and controlling said plurality of switching points such that said assemblies of said lot reach said second point according to said manufacturing priority of said lot and such that said assembles of said lot are substantially contiguous upon reaching said second point.
 13. The method of claim 12 further comprising controlling said plurality of conveyors.
 14. The method of claim 12 wherein said lot is a first lot and said first lot has a lower priority than a second lot, said method further comprising controlling such that said first lot is delayed with respect to said second lot.
 15. The method of claim 14 further comprising controlling such that any separated assembly of said second lot by-passes intervening assemblies of other lots to rejoin said second lot.
 16. The method of claim 12 wherein said assemblies are automotive assemblies. 